Treatment of hydrocarbons



June 9, 1942.

J. D. SEGUY TREATMENT OF HYDROCARBONS Filed July 13, 1940 A555 FROM CRACKING ISOBUTENE 8.

s N-BUTENES 35 ATING ZONE DEHYDROGEN- CATALYTIC POLYMERIZING ZONE \GASES THERMAL TREATING ZONE SEPARATING ZONE LIQUID PRODUCT ISOBUTANE -l8 ms ZONE 33 BUTENES ALKYlzATING lsooc'rlzuas- -19 J N-BUTANE ZONE E J J i HYDROGEN 20 I 28 I 30 HYDROGEN ATING SEPARATING ZONE ZONE 22 -34 r23 25 I A LKYLATE I SEPARATING ZONE 1 EXCESS -24 HYDROGEN ISOOCTANE I INVENTOR JEAN DELATTRE' SEGUY Patented June 9, 1942 Jean Delattre Seguy, Chicago, 111., assignor to Universal Oil Ifroducts Company, Chicago, Ill., a corporation oi Delaware Application July 13, 1940, Serial No. 345,328

2 Claims.

This invention relates to the production of high quality gasoline from gases produced during the cracking of hydrocarbon oils such as crude petroleum, gas oil, topped crude oil, and oils produced from coal or from other sources.

The invention involves a series of individual maining after selective polymerization. Although the individual steps may be known to those skilled in the respective arts, the feature.

steps which are combined so as to cooperate fraction to form liquid products of gasoline boil-' ing range and a residual gas mntaining C4 hydrocarbons; returning said residual gas to the primary gas separating step; dehydrogenating normal butane to produce substantial proportions of butenes and hydrogen; commingling said butenes with said isobutene and normal butenes separated from the gas charged; selectively polymerizing said isobutene and normal butenes to form a product containing substantially no isobutene; separating said product into an iso-octene' fraction, higher boiling polymers, anda mixture of unconverted butenes and normal butane; hydrogenating said iso-octene fraction with hydrogen separated from the original gas and from the normal butane dehydrogenaof the present invention is that they are combined in a novel and advantageous manner so that they cooperate to produce the desired result. -One essential feature of the invention is the thermal treatment applied to a C1-C3 fraction comprising methane, ethane, ethylene, propane, and propane to produce therefrom substantial yields of liquid products and of 4-carbon atom olefins and parafiins. Through the use of this step, additional quantities of butenes and butanes may be made available for subsequent use in the production of iso-octane by alkylation or by polymerization and hydrogenation reactions. In the accompanying drawing, in order to illustrate the process of theinvention without tion products to form a substantially'iso-octane fraction; subjecting isobutane to alkylation by butenes contained in said mixture of unconverted butenes and normal butane to form a substantially saturated alkylation product; separating said alkylation product into unconverted isobutane, recovered normal butane,. and a substantially saturated alkylate; recycling said uncomplicating it with unnecessary details of each specific step and since those skilled in the art are now generallyfamiliar with themajor steps of the process, the general practice of illustrating each specific step in detail has been departed from and a flow .diagram has been used instead. Referring to the accompanying diagram of a typical process flow, a gaseous charging stock obtained from cracking of a hydrocarbon oil is supplied through line -I to separating none 2 whereinare separated hydrogen, a C1C3 hydrocarbon fraction, isobutane, normal butane, and a mixture of isobutene and normal butenes. Separating zone 2 may comprise absorbing, strip:- ping, fractional distilling, solventextractingor azeotropic' distilling; etc. equipment of suitable design for effecting the aforementioned separations.

From separating zone- 2 a C1C3 fraction may be conducted through line 3 to thermal treating zone I which may comprise a reactor of 4 suitable design operating at a temperature in converted isobutane to further alkylation treat-" butenes separated from the gas charged and and paraflins may be recycled through line 8 from the dehyrogenation products to form a polymer fraction containing a s bstantial proportion of iso-octenes, hydrogenation of is'o' octenes by hydrogen recovered in the process, and alkylation of isobutane separated from the charge by n-butenes contained in the gases rethe approximate range of 8001100 F. and under a pressure of the order of 100-2000 pounds per square inch in order to form substantial yields of liquid products and a butene-containing fractionv which may be conducted thence through line 5 to separating zone 6 in which reacted products may be withdrawn through line Ito storage and a gas fraction containing sub.- stantial proportions of 4-carbon atom oleflns a may be conducted therefrom through line 9- to dehydrogenating zone "I which may comprise a tubular reactor or group of reactors maintained at a temperature in the approximate range of 750-1200" F. under a pressure of from substantially atmospheric to approximately 100 pounds per square inch and containing a gra'nul'ar material comprising a major, proportion of a refractory carrier and a relatively smaller proportion of a' compound of greater dehydrogenating activity than said carrier such as an oxide of an element selected from the members of. the

left-hand columns of groups IV, V, and VI of ing catalysts hereinabove set forth are the preferred catalysts, they are not to be considered as a limiting feature of the process for various.

, other dehydrogenating catalystsknown to those skilled in the art may-be employed within the broad scope of this invention.

pressure in the approximate pounds per square inch. I

The resulting polymerization products which consist of normally liquid polymers, containing iso-octen'es, some higher boiling materials, and unconverted gases comprising essentially normal butenes andnormal butane, are withdrawn from the periodic table. Although the dehydrogenat- The conversion products from dehydrogenating zone "I, of which a substantial proportion are normal butenes, may bedirected through, l ne I! to separating zone l2 wherein hydrogen resulting polymerizing zone II through line It to separating zone I! which may comprise a fractional distilling column by which unconverted butenes and normal butane may be separated from the butene polymers. Separating zone I! will ordinarily comprise a fractionating zone wherein liquid polymers boiling above the desired iso-octene from the dehydrogenation of normal butane is 4 separated from the heavier gaseous hydrocarbons comprising essentially normal butenes and unconverted normal butane. Separating zone I! will ordinarily comprise an absorbing zone where hydrogen and light gaseous hydrocarbons such as methane are separated from higher molecular weight hydrocarbons and a distilling or stripping step, wherein said higher molecular weight hydrocarbons are liberated from the absorption me-' dium. However. other means for efiecting'separation may be employed in separating zone-J2 'obviating the necessity of absorbing and stripping steps such as, for example, a compressor all of which are within the broad concepts of this invention. The hydrogen or gas mixture contain ing a substantial proportion of hydrogen separated-in 'separ'ating'zone i2 is directed, in the casehere illustrated, through line I I to line It for use as subsequently described. The normally gaseous hydrocarbons separated in separating zone I I2 and comprising essentially normal butenes and unconverted normal butane may be directed through line ll to cataL'ytic polymerizing zone It, A mixture comprising essentially isobutene and normal butenes separated in separating zone 2 by solvent extraction or by azeotropic distillation, for

' example, in thepresence of sulfur dioxide, may be conducted thence through line to line I4 and ,ber.

therein commingled with the" butene-containing fraction being conducted to Y polymerization in catalytic polymerizing zone I in which isobutene' and a portion of the normal butenes maybe con verted into substantial yields of isomeric octenes hydrogenatable to iso-octanes of high octane number. 7 A sulfuric or phosphoric acid catalyst may be employed in polymerizing zone I5 at atempera ture so regulated in the presence of either of these catalysts as" to effect conversion into polymers of substantially all of the isobutene and a portion of the normal butenes. When sulfuric acid of approximately GO- concentration isthe polymerizing catalyst, temperatures of the order of 80 -200";F. may be used under a pressure suiiicient to force through the plant the mixture of acid and hydrocarbons. .When a phosphoric acid is used as polymerizing. catalyst, generally in the form of acalcined composite with-"a siliceous adsorbent as described in United States Patent No. 1,993,513 and others, polymerization may be effected at a temperature in the approximaterange of 235-350 F. under a fraction are separated and a debutanizingzone wherein residual gases consisting essentially of butenes and butane are separated from said isooctene fraction. Although as described above the fractionating zone will ordinarily precede the debutanizing zone, thisis not essential, and them- 'dividual' zones may be used in reverse order.

The mixture of unconverted butenes and normal butane is withdrawn from separating zone ll .through line 18 to line 28 for-further treatment -mingled mixture of iso-octenes and hydrogen is then introduced-to hydrogenating zone- 2| where- 'in said iso-octene is hydrogenated to an iso-.

octane fraction of big antiknock value generally in the approximate r e of -100 octane num- Hydrogenation in zone 2| isaccomplished in the presence of a catalyst which preferably consists of nickel supported by'a relatively porous siliceous carrier .such as diatomaceous earth. This catalyst may be produced by precipitating nickel" carbonate on diatomaceous earth and forming the composited material into pellets which an dried, calcined, and then reduced with hydrogen at a temperature of approximately "750 F. However, .other hydrogenating'catalysts well known-inthe art such as, for example, oxides of chromium, molybdenum, and tungsten may be employed when desired. Hydrogenation may be carried out preferably under a superatmospheric pressure ranging, for example, from to 300 pounds or'more per square inch and at a temperature in the approximate range of ZOO-500 F. The resulting products including the unused excess hydrogen are directed from zone 2| through line 22 to separating zone 23 wherein the isooctane fraction is separatedfrom any normally gaseous hydrocarbons and hydrogen. The isooctane fraction is directed through line 24 to oooling and storage or elsewhere as desired, and

-' the gases. are removed'from separating zone 23 a through line 25- and discharged from the system to storage or elsewhere or-may, when desired, be

returned by well known means, as through alter- -native line-N, to the hydrogenating zone for reuse of the hydrogen.

l'sobutan'e separated in separating zone 2 from.

other constituents of thegas charged may beconducted therefrom through line 28, and therein commingled with a mixture of unconverted burange of 500-1500 to the process may have the tones and normal butane separated from polymerization products in separating'zone l1, and

conducted thence through line [8 as aforementioned, The 'commingled mixture in line 26 comprising essentially isobutane, butenes, and

normal butane is then introduced to alkylating zone 21 which may comprise a suitable reactor provided with adequate means for agitating, cooling, and/or heating to maintain a temperature in the approximate range of -15 to 200? F.

generally required for-alkyl'ation' in the presence of a chosen alkylating catalyst such as sulfuric acid, hydrogen fluoride, a mixture of boron fluoride and hydrogen fluoride, or aluminum chloride with hydrogen chloride. In the presence of an alkylating catalyst of the types mentioned, it is preferable to utilize a pressure sum cient to maintain in liquid phase a substantial proportion of the reacting hydrocarbona In case a granular calcined composite of an acid of phosphorus and a siliceous adsorbent is employed as alkylating catalyst, the reactor maybe a cylindrical'chamber designed, to operate at a tem- Pyrolysis of the C1-C3 fraction at approxi mately 1000 F. under a pressure of 200 pounds per square inch may yield anomially liquid prodperature in the approximate range of GOO-900 F. and under a pressure in the approximate range of 1000-3000 pounds per. square inch.

Alkylation products and unconverted butanes may be withdrawn from alkylating zone 21 through line 28 to separating zone 29 which may comprise a fractional distilling column of suitable design for separating an unconverted iso-. butane fraction, a recovered normal butane fraction, and a substantially saturated alkylate containinga relatively high proportion of anavia tion gasoline fraction of high antiknock value.

The unconverted isobutane fraction may be recycled from separating zone 29 through lines 30 and 26 to further alkylation in alkylating zone 21. The recovered normal butane fraction may be directed from separating zone 29 through line 3| to line 9; already mentioned, through which normal butane is conducted to dehydrogenating zone Ill. *The substantially saturated alkylate which comprises one of the desired products of the process may be withdrawn from'separating' zone 29 through line 32 to cooling and storage or elsewhere as desired.

The operating conditions which may be e ployed in successfully conducting the process of the invention will vary considerably depending upon the specific type of catalyst employed in each of the zones, and since no novelty is claimed for any of the processes involved in the individual steps of the system nor for the catalysts which may be, used therein, and since the regulation of the operating conditions in each of the individual steps to accomplish the object herein set forth,,when using any of the known catalysts, is within the skill-of those familiar with the arts involved, only those conditions which maybe'employed when using the preferred catalysts are herein disclosed.

The following example of one specific operation of the process will serve' to illustrate satisfactory operating conditions as applied to specific catalysts but should not, however, be considered as.a limitation of the generally broad scope of. the invention: Y

A .gas 'formed in' the thermal cracking of a Trinidad gas oil may be separated intoa hydrogen-containing fraction, a C1-C3 fraction,

normal butane, isobutane, and an isobutenenormal butene: mixture. A typical gas charged composition indicated in Table I. a

' not of gasoline boiling rangeand agaseous fraction containing methane, ethane, propane, and some butanes. Dehydrogenation of the normal butane at 950 F. under substantially atmospheric pressure in the presence of a composite comprising essentially 8% by weight of chromium sesquioxideand 92% by weight'of activated alumina may produce per pass approximately 25% of normal butenes which may be commingled with the 'isobutene and normal butenes separable by solvent extraction of the 4-carb0n atom' hydrocarbon fraction of, the cracked gases charged, and the commingled mixture may then be subjected to contact with a calcined composite of pyrophosphoric acid and diatomaceous earth at approximately 325 F. under a pressure of 600 pounds per square inch to produce normally liq- "uid polymers and uncfonvertedgases comprising essentially normal butenes. and normal butane.

Fractional distillation of the normally liquid polymers may be employed to separate iso-octene from relatively small amounts of higher boiling polymers after which the iso-octenes may be hydrogenated to isomeric octanes utilizing hydrogen formed in the dehydrogenating step of the process. Y

Isobutane contained in the gas charged may be alkylated by butenes contained in the unconverted gases recovered from the catalytic 'polymerizing step and utilizing'as alkylating catalyst sulfuric acid ofapproximately 98% concentration-at a temperature of 45 F. under a pressure of' 300 pounds per square inch. The excess of isobutane and normalbutane commingled with the substantially saturated alkylate may be separated therefrom as by fractional distillation and may then be" recycled to further alkylating dehydrogenating treatments.

.The character of the invention and the type and of results obtainable are evident from the prev ceding' specification and example, although they are not to be considered as imposing undue limitations upon its generally broad scope.

I claim as my invention:

1. A process for producing more valuable products from a gaseous hydrocarbon mixture,

which comprises separating said mixture into at least three" fractions, an isobutane fraction, a normal butane fraction and a fraction comprise ing iso and normal butenes, subjecting said normal butane fraction to dehydrogenation to form butene and hydrogen,1separating butene and unconverted normal butane from said hydrogen,

combining saidbutene andunconverted normal butane with the iso and normal butenes and sub-- Jecting the mixture to polymerization under con- "thefluneactednormal-butane from said gasoline ditions of temperature, pressure and contact time 1 regulated to polymerize substantially all the isobutene and only a portion of the normal butenes to isooetenes leaving a quantity of normal butene iunconverted which is approximately equivalent to the volume of isobutane in said mixture, separating said isooctenes from the normal butane and unconverted butenes, combining said unconoline from the hutene and isobutane,

- and returning the former to the step.

2. The process or claim lturther by the steps which comprise separating a hydrogen fraction from the first named mixture, comverted butenes and the normal butane with said i isobutane fraction and subjectingthe mixture to alkylation to form a substantially saturated gasbining said hydrogen fraction with the hyrlm-v to form isooctane. i 

